1. Field of the Invention
The present invention relates to an operating unit for an endoscope having focusing and/or zooming functions.
2. Description of the Related Art
Japanese Patent Kokai Publication No. 63-269113 discloses an operating unit for an endoscope having focusing and/or zooming functions. The endoscope has an objective optical system forming an image on an image receiving unit of an image transmitting system. The objective optical system and the image receiving unit are both installed in a front end of an insertion unit of the endoscope. To remotely control a relative distance between the objective optical system and the image receiving unit for focussing and/or zooming, the operating unit is equipped with an optical system operating ring 79 for moving one or both of the objective optical system and the image receiving unit back and forth through an operating wire passing through the insertion unit. The optical system operating ring 79 is provided on an eyepiece projecting from the head portion of the operating unit and is juxtaposed to a diopter adjusting ring 121.
The operating ring 79 provided on the eyepiece is located at a position where the fingers of the left hand holding the operating unit cannot reach. Therefore, the operating ring 79 must be operated using the right hand.
In contrast to the diopter adjustment ring 121, which need not be adjusted during endoscopic observation after it has been initially adjusted, the optical system operating ring 79 for performing focusing and/or zooming operations must be operated at a most critical time when the objective diseased part is observed through the endoscope. If the optical system operating ring is operated at this time using the right hand, which must be used for holding the insertion unit, the front end of the insertion unit is unintentionally moved from a position where the objective diseased part can be observed. Consequently, a series of operations, starting with an operation of guiding the front end of the insertion unit to the objective diseased part, must be repeated.